How do you factor #ab - 5a + 4b - 20?

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Answer 1 · 2015-05-14T16:36:00

$ab - 5a + 4b - 20$

Group

$color(red)((ab-5a))+color(blue)((4b-20))$

Extract factor from each group

$color(red)((a)(b-5)) +color(blue)((4)(b-5))$

Extract the $(b-5)$ factor from each term

$(color(red)(a)+color(blue)(4))(b-5)$